记者日前从中科院成都山地所获悉，该所博士蔡延江采用静态箱—气相色谱法，在河南省封丘县对不同施肥制度下玉米—小麦轮作体系的氧化亚氮排放进行了观测研究。结果显示，将一半有机肥与一半无机肥氮配施，能有效降低我国华北平原农田土壤氧化亚氮的排放。相关成果发表在《大气环境》杂志上。
据了解，氧化亚氮是排在二氧化碳、甲烷之后的第三大温室气体，其单分子增温潜势是二氧化碳的298倍，其中农业生产及氮肥施用是氧化亚氮重要的排放源。过量施用氮肥导致的温室气体排放，已成为我国乃至全球农业可持续发展的严重威胁。
此次研究人员通过对比长期定位试验地内不施肥（CK）与有机肥（OM）、有机肥氮和化肥氮各半（HOM）以及化肥氮磷钾（NPK）处理的3年氧化亚氮通量发现，小麦HOM和NPK处理氧化亚氮累积排放量存在显著的年际变化。玉米季和全年氧化亚氮累积排放量虽然在统计学上无明显的年际差异，但其年际变化仍较为明显。
科研人员还发现，不同年份间氧化亚氮排放的差异主要归因于基肥施用后土壤水分含量的差异，基肥施用后立即灌水或降水比翻耕前灌水更能诱导土壤排放氧化亚氮。HOM与OM、NPK相比具有更高的氮肥利用效率，且其单位产量上的氧化亚氮排放量更低。（生物谷Bioon.com）
生物谷推荐的英文摘要
Atmospheric Environment doi.org/10.1016/j.atmosenv.2012.10.038
Nitrous oxide emissions from Chinese maize–wheat rotation systems： A 3-year field measurement
Yanjiang Caia，Weixin Dinga，Jiafa Luob
Nitrous oxide (N2O) fluxes were measured over a 3-year period (2004–2007) in a long-term experimental field. The objectives of the study were to evaluate the interannual variation of N2O emissions from a maize–wheat rotation， under different fertilizer regimes and to determine the key controlling factors. The study involved four treatments： compost (OM)， half compost N plus half inorganic fertilizer-N (HOM)， inorganic fertilizer-N (NPK)， and control (CK) where no N application. The mean annual N2O emission over a 3-year period was 0.30 ± 0.11 kg N2O–N ha1 in the CK treatment， but increased to 1.61 ± 0.10 kg N2O–N ha1 in the HOM treatment， 2.13 ± 0.15 kg N2O–N ha1 in the OM treatment， and 2.76 ± 0.19 kg N2O–N ha1 in the NPK treatment. Differences were significant among treatments. The N2O emission factors of the applied OM， NPK and HOM were 0.61 ± 0.02， 0.82 ± 0.10 and 0.44 ± 0.04%， respectively， at a rate of 300 kg N ha1 year1， indicating that the combined application of compost with inorganic fertilizer significantly reduced N2O emission. Over a maize–wheat rotation year， more than 65% of the annual N2O emission occurred during the maize growing season. There was a large interannual variation in N2O emission in all treatments， albeit not significant either during the maize growing season or at an inter-year scale. This interannual variation was mainly attributable to differences in soil moisture after basal fertilizer application， and irrigation and/or heavy rainfall events immediately following basal fertilization could induce more N2O production than pre-irrigation before plowing. The HOM treatment had higher N fertilizer use efficiency and lowest yield-scaled N2O emissions compared with the OM and NPK treatments. We therefore argue that the combined application of half compost N plus half fertilizer-N will mitigate N2O emissions from soils in the North China plain.
